From f634c6e0a486637959503cf31568013eaa938eec Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Tue, 17 Jan 2023 01:47:51 -0300
Subject: [PATCH] checker: fix postfix var checking break (#16984)

---
 vlib/v/checker/checker.v                       |  2 +-
 .../undefined_var_in_comptime_for_test.out     |  7 +++++++
 .../undefined_var_in_comptime_for_test.vv      | 18 ++++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/checker/tests/undefined_var_in_comptime_for_test.out
 create mode 100644 vlib/v/checker/tests/undefined_var_in_comptime_for_test.vv

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 27e06627c6..2f210b2ccd 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -3508,7 +3508,7 @@ fn (c &Checker) has_return(stmts []ast.Stmt) ?bool {
 
 pub fn (mut c Checker) is_comptime_var(node ast.Expr) bool {
 	return c.inside_comptime_for_field && node is ast.Ident
-		&& (node as ast.Ident).info is ast.IdentVar && ((node as ast.Ident).obj as ast.Var).is_comptime_field
+		&& (node as ast.Ident).info is ast.IdentVar && (node as ast.Ident).kind == .variable && ((node as ast.Ident).obj as ast.Var).is_comptime_field
 }
 
 fn (mut c Checker) postfix_expr(mut node ast.PostfixExpr) ast.Type {
diff --git a/vlib/v/checker/tests/undefined_var_in_comptime_for_test.out b/vlib/v/checker/tests/undefined_var_in_comptime_for_test.out
new file mode 100644
index 0000000000..0da1dc1fa9
--- /dev/null
+++ b/vlib/v/checker/tests/undefined_var_in_comptime_for_test.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/undefined_var_in_comptime_for_test.vv:11:3: error: undefined ident: `fields_len`
+    9 | fn test[U](val U) {
+   10 |     $for field in U.fields {
+   11 |         fields_len++
+      |         ~~~~~~~~~~
+   12 |         println(field)
+   13 |     }
diff --git a/vlib/v/checker/tests/undefined_var_in_comptime_for_test.vv b/vlib/v/checker/tests/undefined_var_in_comptime_for_test.vv
new file mode 100644
index 0000000000..e31ee192cd
--- /dev/null
+++ b/vlib/v/checker/tests/undefined_var_in_comptime_for_test.vv
@@ -0,0 +1,18 @@
+module main
+
+struct Struct {
+	b string
+	a ?string
+	c string
+}
+
+fn test[U](val U) {
+	$for field in U.fields {
+		fields_len++
+		println(field)
+	}
+}
+
+fn test_main() {
+	test(Struct{})
+}